This proposal requests support toward the purchase of an 800 MHz NMR spectrometer that will be used by investigators at the University of California at Berkeley for studies of biomolecular structure, function and dynamics. The principle users will be the groups of Professors Wemmer, Tinoco and Handel, who are already very active in applications of NMR spectroscopy to biological problems. Problems being addressed include the structure of NtrC, a bacterial two-component signaling system, design of sequence specific DNA binding ligands, structures of elements of group I intron RNA and brome mosaic virus RNA 3' end, structures of chemokines and their interacting partners, and proteins with repacked cores. There is also a substantial group of secondary users whose labs are focused on particular biological problems, but have systems which are developed to the point that structural studies are appropriate and would facilitate further biochemical experiments. These users and their areas of research include Professors Marqusee (free energy landscapes for protein folding), Nogales (tubulin interactions, and complexes making up transcription factor IID), Bustamante (group I intron mechanical unfolding and the relationship to structural features), Collins (structures of telomerase components), Berger (structure of Cdc6 and DnaG domains) and Botchan (structure and interactions of E1 and E2 domains).